Evaluating the association between hybrid magnetic resonance positron emission tomography and cardiac-related outcomes in cardiac sarcoidosis

Objectives: To evaluate an extended hybrid MR/PET imaging strategy in cardiac sarcoidosis (CS) employing qualitative and quantitative assessment of PET tracer uptake, and to evaluate its association with cardiac-related outcomes. Background: Invasive endomyocardial biopsy is the gold standard to diagnose CS, but it has poor sensitivity due to the patchy distribution of disease. Imaging with hybrid late gadolinium enhancement (LGE) MR and 18F-fluorodexyglucose (18F-FDG) PET allows simultaneous assessment of myocardial injury and disease activity and has shown promise for improved diagnosis of active CS based on the combined positive imaging outcome, MR(+)PET(+). Methods: 148 patients with suspected CS were enrolled for hybrid MR/PET imaging. Patients were classified based on presence/absence of LGE (MR+/MR-), presence/absence of 18F-FDG (PET+/PET-), and pattern of 18F-FDG uptake (focal/diffuse) into the following categories: MR(+)PET(+)FOCAL, MR(+)PET(+)DIFFUSE, MR(+)PET(-), MR(-)PET(+)FOCAL, MR(-)PET(+)DIFFUSE, MR(-)PET(-). Patients classified as MR(+)PET(+)FOCAL were designated as having active CS [aCS(+)], while all others were considered as having inactive or absent CS and designated aCS(-). Quantitative values of standard uptake value (SUVmax), target-to-background ratio (TBRmax), target-to-normal-myocardium ratio (TNMRmax) and T2 were measured. Occurrence of a cardiac-related clinical outcome was defined as any of the following during the 6-month period after imaging: cardiac arrest, ventricular arrhythmia, complete heart block, need for cardiac resynchronization/defibrillator/pacemaker/monitoring device (CRT-D, ICD/WCD, or ILR). MR/PET imaging results were compared to the presence of the composite clinical outcome. Results: Patients designated aCS(+) had more than 4-fold increased odds of meeting the clinical endpoint compared to aCS(-) (unadjusted odds ratio 4.8; 95% CI 2.0-11.4; p<0.001). TNMRmax achieved an area under the receiver operating characteristic curve of 0.90 for separating aCS(+) from aCS(-). Conclusions: Hybrid MR/PET imaging with an extended image-based classification of CS was statistically associated with clinical outcomes in CS. TNMRmax had high sensitivity and excellent specificity for quantifying the imaging-based classification of active CS.

Diagnostic Value of 18F-FDG PET/CT vs. Chest-Abdomen-Pelvis CT Scan in Management of Patients with Fever of Unknown Origin, Inflammation of Unknown Origin or Episodic Fever of Unknown Origin: A Comparative Multicentre Prospective Study

Fluorodesoxyglucose Positron Emission Tomography (PET/CT) has never been compared to Chest-Abdomen-Pelvis CT (CAPCT) in patients with a fever of unknown origin (FUO), inflammation of unknown origin (IUO) and episodic fever of unknown origin (EFUO) through a prospective and multicentre study. In this study, we investigated the diagnostic value of PET/CT compared to CAPCT in these patients. The trial was performed between 1 May 2008 through 28 February 2013 with 7 French University Hospital centres. Patients who fulfilled the FUO, IUO or EFUO criteria were included. Diagnostic orientation (DO), diagnostic contribution (DC) and time for diagnosis of both imaging resources were evaluated. One hundred and three patients were included with 35 FUO, 35 IUO and 33 EFUO patients. PET/CT showed both a higher DO (28.2% vs. 7.8%, p < 0.001) and DC (19.4% vs. 5.8%, p < 0.001) than CAPCT and reduced the time for diagnosis in patients (3.8 vs. 17.6 months, p = 0.02). Arthralgia (OR 4.90, p = 0.0012), DO of PET/CT (OR 4.09, p = 0.016), CRP > 30 mg/L (OR 3.70, p = 0.033), and chills (OR 3.06, p = 0.0248) were associated with the achievement of a diagnosis (Se: 89.1%, Sp: 56.8%). PET/CT both orients and contributes to diagnoses at a higher rate than CAPCT, especially in patients with FUO and IUO, and reduces the time for diagnosis.